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Spotting tomato blight with a smartphone
29 July 2019
handheld device, which is plugged into a
smartphone, works by sampling the airborne
volatile organic compounds (VOCs) that plants
release through their leaves.
"All plants release VOCs as they 'breathe,' but the
type and concentration of those VOCs changes
when a plant is diseased," says Qingshan Wei, an
assistant professor of chemical and biomolecular
engineering and corresponding author of a paper
on the work. "Each disease has its own signature
profile of VOCs. So, by measuring the type and
concentration of VOCs being released by the plant,
you can determine whether a plant is diseased
and—if it is diseased—which disease it has.
"Our contribution here is the creation of a device
that can be plugged into a smartphone and used to
make those VOC measurements quickly in the
field," says Wei, who is also a faculty member in
NC State's Emerging Plant Disease and Global
Researchers at North Carolina State University have Food Security cluster.
developed a handheld device that can be plugged into a
smartphone so that farmers can identify plant diseases Current disease identification techniques rely on
in the field. The handheld device, which is plugged into a molecular assays, which take hours to perform
smartphone, works by sampling the airborne volatile and—most importantly—have to be done in a lab.
organic compounds that plants release through their
Getting a sample to the lab, where the sample may
leaves. If a farmer suspects that a plant may be
diseased, he or she can take a leaf from the relevant
have to wait to be tested, can delay disease
plant and place it in a test tube. The test tube is then identification by days or weeks.
capped for at least 15 minutes to allow the relevant
VOCs to accumulate. After this incubation period, the "Our technology will help farmers identify diseases
cap is removed and the farmer uses a narrow, plastic more quickly, so they can limit the spread of the
tube to pump the VOC-laden air into a “reader� disease and related crop damage," says Jean
device connected to a smartphone. The air is pumped Ristaino, William Neal Reynolds Distinguished
into a chamber in the reader that contains a paper strip. Professor of Plant Pathology at NC State, co-author
The paper is embedded with an array of chemical
of the paper and director of the cluster. "We are
reagents that change color when they come into contact
with a specific chemical group. By evaluating the
now ready to scale up the technology."
resulting color pattern on the strip, users can determine
the nature of any plant disease that may be affecting the Here's how the technology works. If a farmer
plant. Credit: NC State University suspects that a plant may be diseased, he or she
can take a leaf from the relevant plant and place it
in a test tube. The test tube is then capped for at
least 15 minutes to allow the relevant VOCs to
Researchers at North Carolina State University accumulate. After this incubation period, the cap is
have developed portable technology that allows removed and the farmer uses a narrow, plastic tube
farmers to identify plant diseases in the field. The to pump the VOC-laden air into a "reader" device
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connected to a smartphone. reagents that could be embedded in the paper
strips," says Zheng Li, a postdoctoral researcher at
NC State and first author of the paper. "About half
of the reagents were off-the-shelf organic dyes, but
the other half were gold nanoparticles that we
functionalized to respond to specific chemical
groups. These functionalized nanoparticles allow us
to be more precise in detecting various types of
VOCs."
"We also had to design and build the reader device,
since there is nothing like it on the market," says
Wei.
In proof-of-concept testing, the researchers
demonstrated the device's ability to detect and
classify 10 plant VOCs down to the parts-per-
million level. They were able to detect the late blight
pathogen that caused the Irish famine two days
Researchers at North Carolina State University have after tomato plants were inoculated with the
developed a handheld device that can be plugged into a pathogen. Researchers could also distinguish
smartphone so that farmers can identify plant diseases in
tomato late blight from two other important fungal
the field. The handheld device, which is plugged into a
smartphone, works by sampling the airborne volatile pathogens that produce similar symptoms on
organic compounds that plants release through their tomato leaves. In addition, the researchers showed
leaves.If a farmer suspects that a plant may be diseased, they could detect the pathogen Phytophthora
he or she can take a leaf from the relevant plant and infestans in tomato leaves with greater than 95%
place it in a test tube. The test tube is then capped for at accuracy.
least 15 minutes to allow the relevant VOCs to
accumulate. After this incubation period, the cap is "We've shown that the technology works," Wei
removed and the farmer uses a narrow, plastic tube to says. "There are two areas where we could make it
pump the VOC-laden air into a "reader" device connected
even better. First, we would like to automate the
to a smartphone. The air is pumped into a chamber in the
reader that contains a paper strip. The paper is pattern analysis using software for the smartphone,
embedded with an array of chemical reagents that which would make it easier for farmers to make
change color when they come into contact with a specific disease determinations.
chemical group. By evaluating the resulting color pattern
on the strip, users can determine the nature of any plant
"Second, we envision the development of
disease that may be affecting the plant. Credit: Zheng Li,
customized reader strips that are designed to
NC State University measure the VOCs associated with other diseases
specific to a given crop. Different crops in different
regions face different threats, and we could develop
paper strips that are tailored to address those
The air is pumped into a chamber in the reader that specific concerns.
contains a paper strip. The paper is embedded with
an array of chemical reagents that change color "This kind of innovation is an integral part of the
when they come into contact with a specific goals of the NC State Plant Sciences Initiative,
chemical group. By evaluating the resulting color which aims to develop new technologies that will
pattern on the strip, users can determine the nature improve food production through interdisciplinary
of any plant disease that may be affecting the plant. science," Wei says.
"For this technology to work, we had to develop More information: Non-invasive plant disease
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diagnostics enabled by smartphone-based
fingerprinting of leaf volatiles, Nature Plants (2019).
DOI: 10.1038/s41477-019-0476-y
Provided by North Carolina State University
APA citation: Spotting tomato blight with a smartphone (2019, July 29) retrieved 14 November 2021 from
https://phys.org/news/2019-07-tomato-blight-smartphone.html
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